These two photos are the top and bottom plate of the Orbiting Carbon Observatory (OCO) solar diffuser. Optical design by Brian Sutin, drafting by Tim Wagner, EDM machining and photos by Wire Cut Company.
Orbiting Carbon Observatory needed a deployable solar diffuser that could be placed in front of the normally Earth-observing telescope for calibration. The diffuser had to be lightweight, well diffuse, and not pick up stray light from other parts of the satellite.
The final design consisted of small pyramids with rough surfaces. One place had pyramidal bumps, while the other had pyramidal dents. Small window frames were added on one side to prevent light from crossing to the wrong side of the pyramid at larger angles.
On the launched satellite, the diffuser looks something like the artists rendition below from NASA.